5．
阅读理解
Have you wondered why different animals or pests(害虫)have their particular colors? Colors in them seem to be used mainly
to protect themselves.
Birds, especially seagulls are very fond of
locusts(蝗虫), but birds can't easily catch
locusts because locusts change their colors together with the change of the color
of crops. When crops are green, locusts look green. But when crops are ripe(成熟), locusts take on exactly the same brown color as crops have. Some other
pests with different colors from plants are usually easily found and eaten by their
enemies. So they have to hide themselves in terror for lives and appear only at
night.
If you study the animal life in any part of
the world, you will find the main use of coloring is to protect themselves. Bears,
wolves and other beasts move quietly through forests. They
are usually invisible to the eyes of hunters, because they have the color
much like the barks(树皮) of trees.
An even more strange act remains to be noticed.
A kind of fish living in seas can send out a kind of very black liquid when it faces
danger. While the liquid is sent out, it quickly swims away, and its enemies cannot
find it any more.
